Made changes to TruncateUtF8ToByteSize to cleanup the code.

I made some corrections to my previously submitted function 
TruncateUTF8ToByteSize, in order to clean up the code, 
and use it to truncate sync node titles above 255 bytes. 
BUG=43675
TEST=base/string_util_unittest.cc
Review URL: http://codereview.chromium.org/2632005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@50112 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 6 insertions, 5 deletions

diff --git a/base/string_util.cc b/base/string_util.cc
index 216b047..2488b0b 100644
--- a/base/string_util.cc
+++ b/base/string_util.cc
@@ -486,14 +486,16 @@ bool TrimString(const std::string& input,
 void TruncateUTF8ToByteSize(const std::string& input,
                             const size_t byte_size,
                             std::string* output) {
+  DCHECK(output);
   if (byte_size > input.length()) {
     *output = input;
     return;
   }
-
+  DCHECK_LE(byte_size, static_cast<uint32>(kint32max));
+  // Note: This cast is necessary because CBU8_NEXT uses int32s.
   int32 truncation_length = static_cast<int32>(byte_size);
   int32 char_index = truncation_length - 1;
-  const char* cstr = input.c_str();
+  const char* data = input.data();
 
   // Using CBU8, we will move backwards from the truncation point
   // to the beginning of the string looking for a valid UTF8
@@ -502,7 +504,7 @@ void TruncateUTF8ToByteSize(const std::string& input,
   while (char_index >= 0) {
     int32 prev = char_index;
     uint32 code_point = 0;
-    CBU8_NEXT(cstr, char_index, truncation_length, code_point);
+    CBU8_NEXT(data, char_index, truncation_length, code_point);
     if (!base::IsValidCharacter(code_point) ||
         !base::IsValidCodepoint(code_point)) {
       char_index = prev - 1;
@@ -511,7 +513,6 @@ void TruncateUTF8ToByteSize(const std::string& input,
     }
   }
 
-  DCHECK(output != NULL);
   if (char_index >= 0 )
     *output = input.substr(0, char_index);
   else
diff --git a/base/string_util_unittest.cc b/base/string_util_unittest.cc
index 2fdd62e..7afc0bd 100644
--- a/base/string_util_unittest.cc
+++ b/base/string_util_unittest.cc
@@ -85,7 +85,7 @@ bool Truncated(const std::string& input, const size_t byte_size,
                std::string* output) {
     size_t prev = input.length();
     TruncateUTF8ToByteSize(input, byte_size, output);
-    return prev != (*output).length();
+    return prev != output->length();
 }
 
 }  // namespace